Overview

A graph pattern is to match a list of path patterns in the graph and is composed of three successive parts:

• Match Mode (Optional)
• Path Pattern List
• Graph Pattern WHERE Clause (Optional)

<graph pattern> ::= 
  [ <match mode> ] <path pattern list> [ <graph pattern where clause> ]

<path pattern list> ::= <path pattern> [ { "," <path pattern> }... ]

The path pattern list consists of one or multiple path patterns, enabling the construction of more complex patterns that cannot be expressed by a single path pattern.

Each path pattern is independently matched against the graph, producing a set of paths. These sets are either equi-joined on the common variables (if any exist) or combined using the Cartesian product.

Example Graph

The following examples run against this graph:

To create this graph, run the following query against an empty graph:

INSERT (brainy:User {_id: "U01", name: "Brainy"}),
       (rowlock:User {_id: "U02", name: "rowlock"}),
       (purplechalk:User {_id: "U03", name: "purplechalk"}),
       (quickfox:User {_id: "U04", name: "QuickFox"}),
       (quasar92:User {_id: "U05", name: "Quasar92"}),
       (mochaeach:User {_id: "U06", name: "mochaeach"}),
       (london:City {_id: "C01", name: "London"}),
       (newyork:City {_id: "C02", name: "New York"}),
       (rowlock)-[:Follows]->(brainy),
       (purplechalk)-[:Follows]->(brainy),
       (quickfox)-[:Follows]->(brainy),
       (rowlock)-[:Follows]->(mochaeach),
       (purplechalk)-[:Follows]->(mochaeach),
       (quickfox)-[:Follows]->(mochaeach),
       (quasar92)-[:Follows]->(mochaeach),
       (quickfox)-[:LivesIn]->(london),
       (rowlock)-[:LivesIn]->(newyork),
       (purplechalk)-[:LivesIn]->(newyork)

Connected Paths

To get common followers of Brany and mochaeach who live in New York:

MATCH (:User {name: 'Brainy'})<-[:Follows]-(u:User)-[:Follows]->(:User {name: 'mochaeach'}), 
      (u)-[:LivesIn]->(:City {name: 'New York'})
RETURN u.name

The two path patterns have a common variable u, thus equi-join is performed:

Result:

Disconnected Paths

This graph pattern finds users who follow Brainy and users who live in New York:

MATCH (u1:User)-[:Follows]->(:User {name: 'Brainy'}),
      (u2:User)-[:LivesIn]->(:City {name: 'New York'})
RETURN u1.name, u2.name

The two path patterns have no common variable, thus Cartesian product is performed:

Result:

Match Mode

This feature is not yet supported.

A graph pattern may optionally specify a match mode that applies to all path patterns contained in the graph pattern.

There are two match modes:

• DIFFERENT EDGES: A matched edge is not permitted to bind to more than one edge variable. There are no restrictions on matched nodes.
• REPEATABLE ELEMENTS: There are no restrictions on matched edges or matched nodes. It is implicit when no match mode is specified.

<match mode> ::= 
  <repeatable elements match mode> | <different edges match mode>
  
<repeatable elements match mode> ::= "REPEATABLE ELEMENTS"

<different edges match mode> ::= "DIFFERENT EDGES"

This query finds nodes those connected to U01, but also have connections with other nodes besides U01:

MATCH DIFFERENT EDGES (:User {name: "QuickFox"})-[e1]-(n), (n)-[e2]-(m)
RETURN DISTINCT n

Records that ensure edges are uniquely bound to different variables are retained. Therefore, only nodes U03 and C01 are returned.

If the match mode is DIFFERENT EDGES and if an edge variable has been multiply declared within a graph pattern, then no results are return. See the following two examples:

MATCH DIFFERENT EDGES ()-[e]->(), ()-[e]->()
RETURN e

MATCH DIFFERENT EDGES ()-[e]->()-[e]->()
RETURN e